The invention relates to an emulsifier, a method of preparing said emulsifier, and to its use in various applications, primarily food and cosmetic applications.
Many products encountered in daily life, particularly food and cosmetic products, are examples of colloidal systems. Colloidal systems are characterized by the presence of small particles of solids, liquids or gases homogeneously distributed throughout the volume of a carrier. The particles are often referred to as the dispersed or discontinuous phase of a colloidal system, whereas the carrier is typically referred to as the continuous phase. Typical examples of colloidal systems include ice cream and bread, in which the dispersed phase consists of small air bubbles, and salad dressings in which the dispersed phases is composed of small droplets of liquid oil dispersed in an aqueous, liquid continuous phase.
A colloidal system wherein both the dispersed and the continuous phase are liquids is classified as an emulsion. An emulsion is an intimate mixture of two immiscible liquids wherein one liquid phase is dispersed in the other in the form of small droplets. Traditional emulsions are classified according to the composition of the phases. If the continuous phase is water and the discontinuous phase is oil, the emulsion is classified as an oil-in-water (O/W) emulsion. The reversed situation is referred to as water-in-oil (W/O) emulsion. Generally, O/W emulsions are white and creamy, while W/O emulsions are of darker colour and have a greasy texture.
All colloidal systems, including emulsions, have in common that they typically require stabilization to prevent separation into two phases. There are different stabilization requirements for solid and liquid emulsions. For example, in a fat spread such as margarine, the W/O emulsion is essentially stabilized by crystallized fat in a three dimensional network. A liquid emulsion system is a more dynamic system. When oil is vigorously stirred in water, a crude form of an emulsion is formed. This emulsion will be highly unstable; the system will separate into oil and water layers within a short period of time. It is for stabilizing that emulsifiers are used.
Various chemical products and compositions are used in the food and cosmetic industries as emulsifiers. In many functions, the emulsifiers also function as stabilizer of the viscosity or fluidity of the continuous phase of the emulsion. Typically, it is desired that the emulsion is shelf-stable and the emulsifier may assist in achieving that goal.
Gum arabic is preferred in many applications for its shelf-stability, particularly in refrigerated or frozen storage of emulsions. It has been used as an emulsifier and stabilizer in foods such as confections, syrups, flavour oil emulsions, ice cream and beverages. It is a branched, substituted heteropoly-saccharide characterized by extreme water solubility, low viscosity, and the absence of odour, colour and flavour. It is a naturally occurring gum produced in the Middle East and Africa. It is, however, an expensive product and its supply and quality are unpredictable.
In many applications, alkyl or alkenyl succinated starches can replace gum arabic. Particularly, octenyl succinated starches have found wide spread use as emulsifier. Use of these starches can reduce costs and improve stability in supply.
Starch in itself is not suitable for use as an emulsifier because it lacks the necessary lipophilic groups. It is therefore not compatible with systems comprising water-insoluble substances. Amphiphilic characteristics can be introduced in starch by treating it with a cyclic dicarboxylic acid anhydride, like octenyl succinic anhydride, to form an alkyl or alkenyl dicarboxylic starch. As a result of this modification, the starch is stabilized in aqueous solutions, so that retrogradation will be hindered. A significant advantage of these starches is that their hydrophilicity is retained, while hydrophobicity is introduced.
For many applications, there is an ongoing need for further improvements in emulsion stability, and thus for improved emulsifiers. It is in this context that the present invention was made.